Transition-metal Free Visible Light Photoredox-catalyzed Remote C(sp3)-H Borylation Enabled by 1,5-Hydrogen Atom Transfer

We describe a transition-metal free, photoredox-catalyzed borylation method of unactivated C(sp3)-H bonds via initiated 1,5-hydrogen atom transfer (HAT). The remote borylation was directed by 1,5-HAT of the amidyl radical, which was generated by photocatalytic reduction of hydroxamic acid derivatives. Substrates bearing primary, secondary and tertiary C(sp3)-H bonds could all be accommodated in this remote borylation protocol, giving moderate to good yields of the desired products (up to 92%), and a series of functional groups were tolerated. Mechanistic studies, including radical clock experiments and DFT calculations, gave detailed insight into the 1,5-HAT borylation process

Ti4O7/g-C3N4 Visible Light Photocatalytic Performance on Hypophosphite Oxidation: Effect of Annealing Temperature

The oxidation of hypophosphite to phosphate is the key to recover the phosphorus resource from the hypophosphite wastewater. In the present work, Ti4O7/g-C3N4 composites were synthesized at two different temperatures (100 and 160°C) and their performance on photocatalytic oxidation of hypophosphite under visible light irradiation and the corresponding mechanism were evaluated. A hydrolysis method using g-C3N4 and Ti4O7 was applied to synthesize the Ti4O7/g-C3N4 composites with their hybrid structure and morphology confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS). The annealing temperature significantly affected the photocatalytic performance of Ti4O7/g-C3N4 that the 160-Ti4O7/g-C3N4 composite (fabricated at 160°C) showed the highest oxidation efficiency of hypophosphite of 81% and the highest photocatalytic oxidation rate of 0.467 h−1 comparing with the 100-Ti4O7/g-C3N4 composite (fabricated at 100°C) and pure g-C3N4. The enhanced photocatalytic performance of 160-Ti4O7/g-C3N4 could be ascribed to the effective charge separation and enhanced photoabsorption efficiency. Additionally, electron spin resonance (ESR) results showed that hydroxyl radicals and superoxide anion radicals were mainly responsible to the oxidation of hypophosphite with superoxide anion radicals accounting for a more significant contribution. Moreover, Ti4O7/g-C3N4 photocatalysts showed the remarkable stability in the repetitive experiments

Efficient production of heat-stable antifungal factor through integrating statistical optimization with a two-stage temperature control strategy in Lysobacter enzymogenes OH11

Abstract Background Heat-stable antifungal factor (HSAF) is a newly identified broad-spectrum antifungal antibiotic from the biocontrol agent Lysobacter enzymogenes and is regarded as a potential biological pesticide, due to its novel mode of action. However, the production level of HSAF is quite low, and little research has reported on the fermentation process involved, representing huge obstacles for large-scale industrial production. Results Medium capacity, culture temperature, and fermentation time were identified as the most significant factors affecting the production of HSAF and employed for further optimization through statistical methods. Based on the analysis of kinetic parameters at different temperatures, a novel two-stage temperature control strategy was developed to improve HSAF production, in which the temperature was increased to 32 °C during the first 12 h and then switched to 26 °C until the end of fermentation. Using this strategy, the maximum HSAF production reached 440.26 ± 16.14 mg L− 1, increased by 9.93% than that of the best results from single-temperature fermentation. Moreover, the fermentation time was shortened from 58 h to 54 h, resulting in the enhancement of HSAF productivity (17.95%) and yield (9.93%). Conclusions This study provides a simple and efficient method for producing HSAF that could be feasibly applied to the industrial-scale production of HSAF